Riveting structure of electrode terminal, and cylindrical battery cell, battery pack and vehicle including the same

ABSTRACT

The riveting structure of an electrode terminal for a battery includes a battery housing having a bottom; an electrode terminal riveted through a hole formed in the bottom of the battery housing; and a gasket between the electrode terminal and the battery housing. Also, the electrode terminal includes a body portion inserted into the hole; an outer flange portion extending along an outer surface of the bottom of the battery housing from a first side of the body portion exposed through the outer surface; an inner flange portion extending toward an inner surface of the bottom of the battery housing from a second side of the body portion exposed through the inner surface; and a flat portion on the second side of the body portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional application claims the benefit under 35 U.S.C. §119(a) to Patent Application No. 10-2021-0022881, filed in the Republicof Korea on Feb. 19, 2021, Patent Application No. 10-2021-0022891, filedin the Republic of Korea on Feb. 19, 2021, Patent Application No.10-2021-0022894, filed in the Republic of Korea on Feb. 19, 2021, PatentApplication No. 10-2021-0022897, filed in the Republic of Korea on Feb.19, 2021, Patent Application No. 10-2021-0024424, filed in the Republicof Korea on Feb. 23, 2021, Patent Application No. 10-2021-0030291, filedin the Republic of Korea on Mar. 8, 2021, Patent Application No.10-2021-0030300, filed in the Republic of Korea on Mar. 8, 2021, PatentApplication No. 10-2021-0046798, filed in the Republic of Korea on Apr.9, 2021, Patent Application No. 10-2021-0058183, filed in the Republicof Korea on May 4, 2021, Patent Application No. 10-2021-0077046, filedin the Republic of Korea on Jun. 14, 2021, Patent Application No.10-2021-0084326, filed in the Republic of Korea on Jun. 28, 2021, PatentApplication No. 10-2021-0131205, filed in the Republic of Korea on Oct.1, 2021, Patent Application No. 10-2021-0131207, filed in the Republicof Korea on Oct. 1, 2021, Patent Application No. 10-2021-0131208, filedin the Republic of Korea on Oct. 1, 2021, Patent Application No.10-2021-0131215, filed in the Republic of Korea on Oct. 1, 2021, PatentApplication No. 10-2021-0131225, filed in the Republic of Korea on Oct.1, 2021, Patent Application No. 10-2021-0137001, filed in the Republicof Korea on Oct. 14, 2021, Patent Application No. 10-2021-0137856, filedin the Republic of Korea on Oct. 15, 2021, Patent Application No.10-2021-0142196, filed in the Republic of Korea on Oct. 22, 2021, PatentApplication No. 10-2021-0153472, filed in the Republic of Korea on Nov.9, 2021, Patent Application No. 10-2021-0160823, filed in the Republicof Korea on Nov. 19, 2021, Patent Application No. 10-2021-0163809, filedin the Republic of Korea on Nov. 24, 2021, Patent Application No.10-2021-0165866, filed in the Republic of Korea on Nov. 26, 2021, PatentApplication No. 10-2021-0172446, filed in the Republic of Korea on Dec.3, 2021, Patent Application No. 10-2021-0177091, filed in the Republicof Korea on Dec. 10, 2021, Patent Application No. 10-2021-0194572, filedin the Republic of Korea on Dec. 31, 2021, Patent Application No.10-2021-0194593, filed in the Republic of Korea on Dec. 31, 2021, PatentApplication No. 10-2021-0194610, filed in the Republic of Korea on Dec.31, 2021, Patent Application No. 10-2021-0194611, filed in the Republicof Korea on Dec. 31, 2021, Patent Application No. 10-2021-0194612, filedin the Republic of Korea on Dec. 31, 2021, and Patent Application No.10-2022-0001802, filed in the Republic of Korea on Jan. 5, 2022, all ofwhich are hereby expressly incorporated by reference in their entiretiesinto the present application.

Also, Patent Application No. 10-2021-0007278, filed in the Republic ofKorea on Jan. 19, 2021, is hereby expressly incorporated by reference inits entirety into the present application.

TECHNICAL FIELD

The present disclosure relates to a riveting structure of an electrodeterminal, and a cylindrical battery cell, a battery pack and a vehicleincluding the same.

BACKGROUND ART

Secondary batteries that are easily applicable to various product groupsand have electrical characteristics such as high energy density areuniversally applied not only to portable devices but also to electricvehicles (EVs), hybrid electric vehicles (HEVs) or the like driven by anelectric drive source.

These secondary batteries are attracting attention as a new energysource to improve eco-friendliness and energy efficiency because theyhave the primary advantage that they can dramatically reduce the use offossil fuels as well as the secondary advantage that no by-products aregenerated from the use of energy.

Secondary batteries currently widely used in the art include lithium ionbatteries, lithium polymer batteries, nickel cadmium batteries, nickelhydrogen batteries, nickel zinc batteries, and the like. A unitsecondary battery cell has an operating voltage of about 2.5V to 4.5V.Therefore, when a higher output voltage is required, a battery pack isconfigured by connecting a plurality of battery cells in series. Inaddition, a plurality of battery cells may be connected in parallel toform a battery pack according to the charge/discharge capacity requiredfor the battery pack. Accordingly, the number of battery cells includedin the battery pack and the form of electrical connection may bevariously set according to the required output voltage and/orcharge/discharge capacity.

Meanwhile, as a kind of secondary battery cell, there are knowncylindrical, rectangular, and pouch-type battery cells. In the case of acylindrical battery cell, a separator serving as an insulator isinterposed between a positive electrode and a negative electrode, andthey are wound to form an electrode assembly in the form of a jellyroll, which is inserted into a battery can together with an electrolyteto configure a battery. In addition, a strip-shaped electrode tab may beconnected to an uncoated portion of each of the positive electrode andthe negative electrode, and the electrode tab electrically connects theelectrode assembly and an electrode terminal exposed to the outside. Forreference, the positive electrode terminal is a cap plate of a sealingbody that seals the opening of the battery can, and the negativeelectrode terminal is the battery can.

However, according to the conventional cylindrical battery cell havingsuch a structure, since current is concentrated in the strip-shapedelectrode tab coupled to the uncoated portion of the positive electrodeand/or the uncoated portion of the negative electrode, the currentcollection efficiency is not good due to large resistance and large heatgeneration due to a small cross section area of the strip-shapedelectrode tab.

For small cylindrical battery cells with a form factor of 18650 or21700, resistance and heat are not a major issue. However, when the formfactor is increased to apply the cylindrical battery cell to an electricvehicle, the cylindrical battery cell may ignite while a lot of heat isgenerated around the electrode tab during the rapid charging process.

In order to solve this problem, there is provided a cylindrical batterycell (so-called tab-less cylindrical battery cell) in which the uncoatedportion of the positive electrode and the uncoated portion of thenegative electrode are designed to be positioned at the top and bottomof the jelly-roll type electrode assembly, respectively, and the currentcollecting plate is welded to the uncoated portion to improve thecurrent collecting efficiency.

FIGS. 1 to 3 are diagrams showing a process of manufacturing a tab-lesscylindrical battery cell. FIG. 1 shows the structure of an electrodeplate, FIG. 2 shows a process of winding the electrode plate, and FIG. 3shows a process of welding a current collecting plate to a bent surfaceof an uncoated portion. FIG. 4 is a sectional view showing the tab-lesscylindrical battery cell, taken along a longitudinal direction (Y).

Referring to FIGS. 1 to 4, a positive electrode plate 10 and a negativeelectrode plate 11 have a structure in which a sheet-shaped currentcollector 20 is coated with an active material 21, and include anuncoated portion 22 at one long side along the winding direction X.

An electrode assembly A is manufactured by sequentially stacking thepositive electrode plate 10 and the negative electrode plate 11 togetherwith two sheets of separators 12 as shown in FIG. 2 and then windingthem in one direction X. At this time, the uncoated portions of thepositive electrode plate 10 and the negative electrode plate 11 arearranged in opposite directions.

After the winding process, the uncoated portion 10 a of the positiveelectrode plate 10 and the uncoated portion 11 a of the negativeelectrode plate 11 are bent toward the core. After that, currentcollecting plates 30, 31 are welded and coupled to the uncoated portions10 a, 11 a, respectively.

An electrode tab is not separately coupled to the positive electrodeuncoated portion 10 a and the negative electrode uncoated portion 11 a,the current collecting plates 30, 31 are connected to external electrodeterminals, and a current path is formed with a large cross-sectionalarea along the winding axis direction of electrode assembly A (see anarrow in FIG. 3), which has an advantage of lowering the resistance ofthe battery cell. This is because resistance is inversely proportionalto the cross-sectional area of the path through which the current flows.

However, when the form factor of the cylindrical battery cell increasesand the magnitude of the charging current during rapid chargingincreases, the heat problem also occurs again in the tab-lesscylindrical battery cell.

Specifically, the conventional tab-less cylindrical battery cell 40includes a battery can 41 and a sealing body 42 as shown in FIG. 4. Thesealing body 42 includes a cap plate 42 a, a sealing gasket 42 b and aconnection plate 42 c. The sealing gasket 42 b surrounds the edge of thecap plate 42 a and is fixed by a crimping portion 43. In addition, theelectrode assembly A is fixed in the battery can 41 by a beading portion44 to prevent vertical movement.

Typically, the positive electrode terminal is the cap plate 42 a of thesealing body 42, and the negative electrode terminal is the battery can41. Accordingly, the current collecting plate 30 coupled to the uncoatedportion 10 a of the positive electrode plate 10 is electricallyconnected to the connection plate 42 c attached to the cap plate 42 athrough a lead 45 in the form of a strip. In addition, the currentcollecting plate 31 coupled to the uncoated portion 11 a of the negativeelectrode plate 11 is electrically connected to the bottom of thebattery can 41. An insulator 46 covers the current collecting plate 30to prevent the battery can 41 and the uncoated portion 10 a of thepositive electrode plate 10 having different polarities from contactingeach other and causing a short circuit.

When the current collecting plate 30 is connected to the connectionplate 42 c, the lead 45 in the form of a strip is used. The lead 45 isseparately attached to the current collecting plate 30 or ismanufactured integrally with the current collecting plate 30. However,since the lead 45 is in the form of a thin strip, its cross-sectionalarea is small, and thus a lot of heat is generated when the rapidcharging current flows. In addition, the excessive heat generated fromthe lead 45 is transferred to the electrode assembly A to shrink theseparator 12, which may cause an inner short circuit that is a maincause of thermal runaway.

The lead 45 also occupies a significant installation space within thebattery can 41. Therefore, the cylindrical battery cell 40 including thelead 45 has low space efficiency, so there is a limit in increasing theenergy density.

Moreover, in order to connect the conventional tab-less cylindricalbattery cells 40 in series and/or in parallel, it is necessary toconnect a bus bar component to the cap plate 42 a of the sealing body 42and the bottom surface of the battery can 41, which deteriorates thespace efficiency. A battery pack mounted on an electric vehicle includeshundreds of cylindrical battery cells 40. Therefore, the inefficiency ofthe electrical wiring causes considerable inconvenience in the assemblyprocess of the electric vehicle and the maintenance of the battery pack.

DISCLOSURE Technical Problem

The present disclosure is designed to solve the problems of the relatedart, and therefore the present disclosure is directed to lowering theinner resistance of a cylindrical battery cell and increasing the energydensity by improving an electrode terminal structure of the cylindricalbattery cell to increase the space efficiency in a battery can.

The present disclosure is also directed to improving the electrodeterminal structure of a cylindrical battery cell to solve the internalheating problem caused during rapid charging by expanding thecross-sectional area of a current path.

The present disclosure is also directed to providing a cylindricalbattery cell having an improved structure that allows electrical wiringfor serial and/or parallel connection of the cylindrical battery cellsto be performed at one side of the cylindrical battery cells.

The present disclosure is also directed to providing a battery packmanufactured using the cylindrical battery cell with an improvedstructure and a vehicle including the battery pack.

However, the technical objects to be solved by the present disclosureare not limited to the above, and other objects not mentioned hereinwill be clearly understood by those skilled in the art from thefollowing disclosure.

Technical Solution

In one aspect of the present disclosure, there is provided a rivetingstructure of an electrode terminal for a battery, comprising: a batteryhousing having a bottom; an electrode terminal riveted through a holeformed in the bottom of the battery housing; and a gasket between theelectrode terminal and the battery housing, wherein the electrodeterminal includes: a body portion inserted into the hole; an outerflange portion extending along an outer surface of the bottom of thebattery housing from a first side of the body portion exposed throughthe outer surface; an inner flange portion extending toward an innersurface of the bottom of the battery housing from a second side of thebody portion exposed through the inner surface; and a flat portion onthe second side of the body portion.

Preferably, the flat portion may be parallel with the inner surface ofthe bottom of the battery housing.

Preferably, an angle between the inner flange portion and the innersurface of the bottom of the battery housing may be in a range of 0° to60°.

Preferably, a recess may be provided between the inner flange portionand the flat portion.

In an embodiment, the recess may have an asymmetric cross section.

In another embodiment, the asymmetric cross section of the recess mayinclude a sidewall and an inclined surface of the inner flange portionconnected to an end of the sidewall.

In still another embodiment, the sidewall may be perpendicular to theinner surface of the bottom of the battery housing.

In still another embodiment, the sidewall may be inclined toward theflat portion.

Preferably, the inner flange portion may have a gradually decreasingthickness in a direction extending away from the body portion.

Preferably, the gasket may include an outer gasket between the outerflange portion and the outer surface of the bottom of the batteryhousing, and an inner gasket between the inner flange portion and theinner surface of the bottom of the battery housing, and the inner gasketmay have a varying thickness.

In an embodiment, a region of the inner gasket between an inner edge ofthe inner surface of the bottom of the battery housing and the innerflange portion may have a relatively smaller thickness than a remainderof the inner gasket.

In another embodiment, a region of the inner gasket between the batteryhousing and the body portion may have a gradually decreasing thicknessin a direction extending away from the outer flange portion.

In still another embodiment, a region of the inner gasket between theinner surface of the bottom of the battery housing and a region near anend of the inner flange portion may have a smaller thickness than aremainder of the inner gasket.

In still another embodiment, the inner edge of the hole may include afacing surface that faces the inner flange portion.

In still another embodiment, the inner gasket may extend outwardlypassed than the inner flange portion.

In still another embodiment, a height of the flat portion may be equalto or larger than a height of an end of the inner gasket based on theinner surface of the bottom of the battery housing.

In still another embodiment, a height of the flat portion may be equalto or larger than a height of the inner flange portion based on theinner surface of the bottom of the battery housing.

In still another embodiment, a height of the inner flange portion may belarger than a height of an end of the inner gasket based on the innersurface of the bottom of the battery housing.

Preferably, a height of the inner flange portion may be 0.5 mm to 3.0 mmbased on the inner surface of the bottom of the battery housing.

Preferably, a height of the electrode terminal extending from a lowersurface of the outer flange portion to a surface of the flat portion maybe 4 mm to 7 mm.

Preferably, a height of the outer flange portion may be 0.8 mm or morebased on the outer surface of the bottom of the battery housing.

Preferably, at least a portion of the outer gasket may be exposed to theoutside of the outer flange portion, and a width of the exposed portionof the outer gasket measured in a direction parallel to the outersurface of the bottom of the battery housing may be 0.1 mm to 1 mm.

Preferably, a radius from a center of the body portion to an edge of theouter flange portion may be 10% to 70% of a radius of the bottom of thebattery housing.

Preferably, a radius from a center of the body portion to an edge of theflat portion may be 4% to 30% of a radius of the bottom of the batteryhousing.

Preferably, a compression ratio of the inner gasket is 30% to 90%, and,and the compression ratio is a ratio of thickness change at a maximumcompression point to a thickness before compression of the gasket.

More preferably, the inner gasket may include polybutyleneterephthalate, polyethylene fluoride, or polypropylene, and thecompression ratio of the inner gasket may be 50% to 90%.

In another aspect of the present disclosure, there is also provided abattery, comprising: an electrode assembly in which a first electrodeand a second electrode wound with a separator therebetween, each of thefirst electrode and the second electrode has a first portion coated withan active material and a second portion, wherein the second portion ofthe first electrode and the second portion of the second electrode areextended from opposite ends of the electrode assembly and exposed to theoutside of the separator; a battery housing accommodating the electrodeassembly and electrically connected to the first electrode, the batteryhousing having a first end with a first opening and a second endopposite the first end; an electrode terminal riveted through a hole inthe second end of the battery housing and electrically connected to thesecond electrode; the electrode terminal including: a body portioninserted into the hole; an outer flange portion extending along an outersurface of the second end of the battery housing from a first side ofthe body portion exposed through the outer surface; an inner flangeportion extending toward an inner surface of the second end of thebattery housing from a second side of the body portion exposed throughthe inner surface; and a flat portion on the second side of the bodyportion, a gasket between the electrode terminal and the batteryhousing; and a sealing body sealing the first opening of the first endof the battery housing so as to be insulated from the battery housing.

In an embodiment, the battery housing may include a beading portionformed in a region adjacent to the first end of the battery housingwhich is pressed-in into the battery housing, and the sealing body mayinclude a cap having no polarity and a sealing gasket between an edge ofthe cap and the first end of the battery housing.

In another embodiment, the battery housing may further include acrimping portion extended and bent into the inside of the batteryhousing to surround and fix the edge of the cap together with thesealing gasket.

Preferably, the cap may include a vent notch that ruptures when apressure inside the battery housing exceeds a threshold pressure.

Preferably, the vent notch may be ruptured when the pressure inside thebattery housing is in a range of 15 kgf/cm² to 35 kgf/cm².

In still another embodiment, the cylindrical battery according to thepresent disclosure may further comprise a first current collecting unitcoupled to the second portion of the first electrode, and at least apart of an edge of the first current collecting unit not in contact withthe second portion of the first electrode may be between the beadingportion and the sealing gasket and fixed by the crimping portion.

Preferably, at least a part of the edge of the first current collectingunit may be fixed to an inner circumference of the beading portionadjacent to the crimping portion by welding.

In still another embodiment, the cylindrical battery according to thepresent disclosure may further comprise a second current collecting unitcoupled to the second portion of the second electrode plate, and atleast a part of the second current collecting unit may be coupled to theflat portion of the electrode terminal.

Preferably, the second current collecting unit and the flat portion ofthe electrode terminal may be coupled through welding, and a tensileforce of a weld between the second current collecting unit and the flatportion of the electrode terminal may be 2 kgf or above.

Preferably, a diameter of a welding pattern exposed on a surface of thesecond current collecting unit may be 2 mm or more.

Preferably, a diameter of the flat portion of the electrode terminal maybe 3 mm to 14 mm.

Preferably, a ratio of an area of a welding pattern exposed on a surfaceof the second current collecting unit to an area of the flat portion ofthe electrode terminal may be 2.04% to 44.4%.

In still another embodiment, the cylindrical battery according to thepresent disclosure may further comprise an insulator between the secondcurrent collecting unit and an inner surface of the second end of thebattery housing and between an inner surface of a sidewall of thebattery housing and the electrode assembly.

Preferably, the insulator may have a welding hole formed to expose theflat portion of the electrode terminal toward the second currentcollecting unit and cover a surface of the second current collectingunit and an edge of one side of the electrode assembly.

Preferably, a height from the inner surface of the second end of thebattery housing to the flat portion of the electrode terminal may beequal to or smaller than a thickness of the insulator.

Preferably, the gasket may include an outer gasket between the outerflange portion and the outer surface of the second end of the batteryhousing; and an inner gasket between the inner flange portion and theinner surface of the second end of the battery housing.

Preferably, an end of the inner gasket may be exposed to the outside ofthe inner flange portion.

In still another embodiment, the welding hole may expose the flatportion of the electrode terminal and the inner flange portion.

In still another embodiment, the welding hole may expose the flatportion of the electrode terminal, the inner flange portion and theinner gasket.

In still another embodiment, in the cylindrical battery cell accordingto the present disclosure, a first bus bar terminal may be electricallycoupled to a surface of the electrode terminal, and a second bus barterminal may be electrically coupled to the outer surface of the secondend of the battery housing.

Preferably, the first bus bar terminal may overlap with the electrodeterminal on a plane to form a first overlapping region, and the secondbus bar terminal may overlap with the outer surface of the second end ofthe battery housing to form a second overlapping region, and a diameterof the electrode terminal and a width of the outer surface of the secondend of the battery housing may satisfy the following relationalexpression,

W ₁ ≤E ₁ ≤D−2R _(d)−2G−2W ₂

E ₂=0.5*(D−2R _(d)−2G−E ₁)

(E₁: diameter of the outer flange portion 50 b of the electrodeterminal, E₂: width of an exposed surface parallel to a surface of theelectrode terminal in the outer surface of the second end of the batteryhousing, D: diameter of the battery housing, R_(d): width of a roundregion at an edge of the battery housing measured on a plane, G:exposure width of the outer gasket through an edge of the electrodeterminal, W₁: maximum value among distances between any two pointsselected in an edge of the first overlapping region, W₂: maximum valueamong distances between two points where a plurality of linear linespassing through the center of the electrode terminal meet an edge of thesecond overlapping region).

In still another embodiment, a ratio of a diameter of the cylindricalbattery to a height of the battery may be greater than 0.4.

In another aspect of the present disclosure, there is also provided abattery pack comprising a plurality of cylindrical batteries describedabove.

Preferably, the plurality of cylindrical batteries may be arranged in apredetermined number of columns, and the electrode terminal and theouter surface of the second end of the battery housing of eachcylindrical battery of the plurality of batteries may be disposed toface upward.

Preferably, the battery pack according to the present disclosure maycomprise a plurality of bus bars connecting the plurality of batteriesin series and in parallel, the plurality of bus bars may be disposedabove the plurality of cylindrical batteries, and each bus bar of theplurality of bus bars may include a body portion extending betweenelectrode terminals of adjacent cylindrical batteries; a plurality offirst bus bar terminals respectively extending in one side directionfrom the body and electrically coupled to the electrode terminal of thebattery located in the one side direction; and a plurality of second busbar terminals respectively extending in the other side direction fromthe body and electrically coupled to the outer surface of the second endof the battery housing of the cylindrical batteries located in the otherside direction.

Preferably, an AC resistance of the battery measured between theelectrode terminal and the outer surface of the second end of thebattery housing may be 4 milliohms (mohm) or less.

In another aspect of the present disclosure, there is also provided avehicle comprising the battery pack described above.

In still another embodiment, an electrode terminal for a batteryaccording to the present disclosure may further comprise a body having atop surface, a lower surface and an outer surface, an outer flangeextending from the outer surface of the body and capable of extendingalong an outer surface of a bottom of a battery housing, an inner flangeextending from the outer surface of the body, the inner flange beingabove the outer flange and the top surface on the body capable ofcontacting a current collecting unit.

The top surface on the body may be above the inner flange.

The top surface on the body may be flat.

The electrode terminal may further comprise a recess between the bodyand the inner flange.

The recess may have a first surface formed by the outer surface of thebody and a second surface formed by an upper surface of the innerflange.

The first surface and second surface may be asymmetrical.

An angle between the inner flange and the outer flange may be between 0°to 60°.

Advantageous Effects

According to an embodiment of the present disclosure, it is possible tolower the inner resistance of a cylindrical battery cell and increasethe energy density by improving an electrode terminal structure of thecylindrical battery cell to increase the space efficiency in a batterycan.

According to another embodiment of the present disclosure, it ispossible to solve the internal heating problem caused during rapidcharging by improving the electrode terminal structure of a cylindricalbattery cell to expand the cross-sectional area of a current path.

According to still another embodiment of the present disclosure,electrical wiring for serial and/or parallel connection of thecylindrical battery cells may be performed at one side of thecylindrical battery cells.

According to still another embodiment of the present disclosure, it ispossible to provide a battery pack manufactured using the cylindricalbattery cell with an improved structure and a vehicle including thebattery pack.

DESCRIPTION OF DRAWINGS

The accompanying drawings illustrate a preferred embodiment of thepresent disclosure and together with the foregoing disclosure, serve toprovide further understanding of the technical features of the presentdisclosure, and thus, the present disclosure is not construed as beinglimited to the drawing.

FIG. 1 is a plan view showing a structure of an electrode plate used fora conventional tab-less cylindrical battery cell.

FIG. 2 is a diagram showing a process of winding an electrode assemblyincluded in the conventional tab-less cylindrical battery cell.

FIG. 3 is a diagram showing a process of welding a current collectingplate to a bent surface of an uncoated portion in the electrode assemblyof FIG. 2.

FIG. 4 is a sectional view showing the conventional tab-less cylindricalbattery cell, taken along a longitudinal direction (Y).

FIG. 5 is a sectional view showing a riveting structure of an electrodeterminal according to an embodiment of the present disclosure.

FIG. 6a is an enlarged sectional view showing a portion indicated by adotted circle in FIG. 5.

FIG. 6b is a partially enlarged sectional view showing a rivetingstructure of an electrode terminal according to another embodiment ofthe present disclosure.

FIG. 6c is a plan view of a top of the flat portion of the terminalshowing the welding pattern.

FIG. 7a is a sectional view showing a cylindrical battery cell accordingto an embodiment of the present disclosure, taken along a longitudinaldirection (Y).

FIG. 7b is a sectional view showing a cylindrical battery cell accordingto another embodiment of the present disclosure, taken along alongitudinal direction (Y).

FIG. 8 is a plan view exemplarily showing an electrode plate structureaccording to a preferred embodiment of the present disclosure.

FIG. 9 is a sectional view showing an electrode assembly in which asegment structure of an uncoated portion of the electrode plateaccording to an embodiment of the present disclosure is applied to afirst electrode plate and a second electrode plate, taken along thelongitudinal direction (Y).

FIG. 10a is a sectional view showing an electrode assembly in which theuncoated portion is bent according to an embodiment of the presentdisclosure, taken along the longitudinal direction (Y).

FIG. 10b is a perspective view showing the electrode assembly in whichthe uncoated portion is bent according to an embodiment of the presentdisclosure.

FIG. 11 is a top plan view showing that a plurality of cylindricalbattery cells according to an embodiment of the present disclosure areconnected in series and in parallel using a bus bar.

FIG. 12a is a partially enlarged view of FIG. 11.

FIGS. 12b and 12c are diagrams exemplarily showing parameters used indefining a diameter of the electrode terminal and an exposure width ofan outer surface of a bottom of a battery can according to an embodimentof the present disclosure.

FIG. 13 is a diagram showing a schematic configuration of a battery packincluding the cylindrical battery cells according to an embodiment ofthe present disclosure.

FIG. 14 is a diagram showing a schematic configuration of a vehicleincluding the battery pack according to an embodiment of the presentdisclosure.

BEST MODE

Hereinafter, preferred embodiments of the present disclosure will bedescribed in detail with reference to the accompanying drawings. Priorto the description, it should be understood that the terms used in thespecification and the appended claims should not be construed as limitedto general and dictionary meanings, but interpreted based on themeanings and concepts corresponding to technical aspects of the presentdisclosure on the basis of the principle that the inventor is allowed todefine terms appropriately for the best explanation.

Therefore, the description proposed herein is just a preferable examplefor the purpose of illustrations only, not intended to limit the scopeof the disclosure, so it should be understood that other equivalents andmodifications could be made thereto without departing from the scope ofthe disclosure.

In addition, in order to help understanding of the invention, in theaccompanying drawings, some components may not be drawn to scale, buttheir dimensions may be exaggerated. Also, the same reference numbersmay be assigned to the same components in different embodiments.

When it is explained that two objects are identical, this means thatthese objects are ‘substantially identical’. Accordingly, thesubstantially identical objects may include deviations considered low inthe art, for example, deviations within 5%. Also, when it is explainedthat certain parameters are uniform in a predetermined region, this maymean that the parameters are uniform in terms of an average.

A cylindrical battery cell according to an embodiment of the presentdisclosure may include an electrode terminal riveted to the bottom of abattery can.

FIG. 5 is a sectional view showing a riveting structure of an electrodeterminal 50 according to an embodiment of the present disclosure, andFIG. 6a is an enlarged sectional view showing a portion indicated by adotted circle in FIG. 5.

Referring to FIGS. 5 and 6 a, the riveting structure of the electrodeterminal 50 according to the embodiment may include a cylindricalbattery can 51 having one open side, an electrode terminal 50 rivetedthrough a perforation hole 53 formed in a bottom 52 of the battery can51, and a rivet gasket 54 interposed between the electrode terminal 50and the battery can 51. Herein, the battery can 51 is one example of thebattery housing in the cylindrical battery.

The battery can 51 is made of a conductive metal material. In oneexample, the battery can 51 may be made of a steel, an aluminum,stainless steel or the like, but the present disclosure is not limitedthereto. The inner and outer surfaces of the battery can 51 may becoated with a Ni plating layer.

The electrode terminal 50 is made of a conductive metal material. In oneexample, the electrode terminal 50 may be made of a steel, an aluminum,stainless steel or the like, but the present disclosure is not limitedthereto. The electrode terminal 50 may be made of 10 series aluminumalloy, which is easy to rivet and has low resistance.

The rivet gasket 54 may be made of a polymer resin having insulation andelasticity. In one example, the rivet gasket 54 may be made ofpolypropylene, polybutylene terephthalate, polyethylene fluoride, or thelike, but the present disclosure is not limited thereto.

Preferably, the electrode terminal 50 may include a body portion 50 ainserted into the perforation hole 53, an outer flange portion 50 bextending along an outer surface 52 a from the circumference of a firstside of the body portion 50 a exposed through the outer surface 52 a ofthe bottom 52 of the battery can 51, an inner flange portion 50 cextending toward an inner surface 52 b from the circumference of asecond side of the body portion 50 a exposed through the inner surface52 b of the bottom 52 of the battery can 51, and a flat portion 50 dprovided on the second side of the body portion 50 a.

Preferably, the flat portion 50 d and the inner surface 52 b of thebottom 52 of the battery can 51 may be parallel to each other. Here, theterm ‘parallel’ means substantially parallel when observed with thenaked eye.

According to an embodiment, the angle (0) between the inner flangeportion 50 c and the inner surface 52 b of the bottom 52 of the batterycan 51 may be 0° to 60°. The size of the angle is determined by thecaulking strength when the electrode terminal 50 is installed in theperforation hole 53 of the battery can 51 by a caulking method. In oneexample, as the caulking strength increases, the angle (0) may decreaseto 0°. If the angle exceeds 60°, the sealing effect of the rivet gasket54 may be deteriorated.

According to another embodiment, a recess 55 may be provided between theinner flange portion 50 c and the flat portion 50 d. The recess 55 mayhave a sectional structure of an asymmetric groove. In one example, theasymmetric groove may have an approximately V shape. The asymmetricgroove may include a sidewall 55 a of the flat portion 50 d and aninclined surface 55 b of the inner flange portion 50 c connected to anend of the sidewall 55 a. The sidewall 55 a may be substantiallyperpendicular to the inner surface 52 b of the bottom 52 of the batterycan 51. The term ‘vertical’ means substantially vertical when observedwith the naked eye. As will be explained later, the sidewall 55 a may beinclined toward the flat portion 50 d. The recess 55 is formed by theshape of a caulking jig when the electrode terminal 50 is installed inthe perforation hole 53 of the battery can 51 in a caulking method.

Preferably, the thickness of the inner flange portion 50 c may graduallydecrease as being farther away from the body portion 50 a of theelectrode terminal 50.

According to another embodiment, the rivet gasket 54 may include anouter gasket 54 a interposed between the outer flange portion 50 b andthe outer surface 52 a of the bottom 52 of the battery can 51, and aninner gasket 54 b interposed between the inner flange portion 50 c andthe inner surface 52 b of the bottom 52 of the battery can 51.Preferably, the outer gasket 54 a and the inner gasket 54 b are dividedbased on the outer surface 52 a of the bottom of the battery can 51.

The outer gasket 54 a and the inner gasket 54 b may have differentthicknesses depending on their locations. Preferably, a region of theinner gasket 54 b interposed between the inner flange portion 50 c andan inner edge 56 of the perforation hole 53 connected to the innersurface 52 b of the bottom 52 of the battery can 51 may have arelatively smaller thickness. Preferably, a minimum thickness point maybe present in a gasket region interposed between the inner edge 56 ofthe perforation hole 53 and the inner flange portion 50 c. In addition,the inner edge 56 of the perforation hole 53 may include a facingsurface 57 that faces the inner flange portion 50 c.

Meanwhile, the top and bottom of the inner wall of the perforation hole53 perpendicular to the bottom 52 of the battery can 51 are chamfered(corner-cut) to form a tapered surface toward the electrode terminal 50.However, the top and/or bottom of the inner wall of the perforation hole53 may be transformed into a smooth curved surface with curvature. Inthis case, the stress applied to the gasket 54 near the top and/orbottom of the inner wall of the perforation hole 53 may be more relaxed.

Preferably, the inner gasket 54 b may extend longer than the innerflange portion 50 c while forming an angle of 0° to 60° with the innersurface 52 b of the bottom 52 of the battery can 51.

In another embodiment, the height (H1) of the flat portion 50 d based onthe inner surface 52 b of the bottom 52 of the battery can 51 may beequal to or greater than the height (H2) of the end of the inner gasket54 b. In addition, the height (H1) of the flat portion 50 d based on theinner surface 52 b of the bottom 52 of the battery can 51 may be equalto or greater than the height (H3) of the end of the inner flangeportion 50 c. Here, the height H2 is the maximum height of the end ofthe inner gasket 54 b measured based on the inner surface 52 b. Inaddition, the height H3 is the maximum height of the end of the innerflange portion 50 c measured based on the inner surface 52 b.

If the height parameters H1, H2 and H3 satisfy the conditions, it ispossible to prevent the inner flange portion 50 c and the inner gasket54 b from interfering with other components.

Preferably, the height (H3) of the inner flange portion 50 c may be 0.5mm to 3.0 mm. If the height (H3) of the inner flange portion 50 c isless than 0.5 mm, sufficient sealing properties are not ensured. Inaddition, if the height (H3) of the inner flange portion 50 c exceeds 3mm, the inner space of the battery can 51 that can be occupied by theelectrode assembly is reduced.

Preferably, the height (H4) of the electrode terminal 50 may be 1.5 mmto 7 mm. The height (H4) of the electrode terminal 50 corresponds to adistance from the lower surface of the outer flange portion 50 b to theflat portion 50 d. If the height (H4) of the electrode terminal 50 isless than 1.5 mm, it is difficult to increase the height of the innerflange portion 50 c to the extent that sealing properties can be secureddue to the thickness of the bottom 52 of the battery can 51. Forreference, the thickness of the battery can 51 bottom 52 is about 0.5 mmto 1 mm. In addition, if the height (H4) of the electrode terminal 50exceeds 7 mm, the inner space of the battery can 51 that can be occupiedby the electrode assembly decreases and the height of the cellincreases, and thus the energy density per unit volume decreases asmuch. When H3 and H4 satisfy the above numerical ranges, it is possibleto sufficiently secure the sealing properties of the electrode terminal50 without reducing the space inside the battery can 51.

In another embodiment, the height (H5) of the outer flange portion 50 bmay be 0.8 mm or more based on the outer surface 52 a of the bottom 54of the battery can 51. If the height (H5) of the outer flange portion 50b is less than 0.8 mm, the outer flange portion 50 b may be deformedwhen the electrode terminal 50 is riveted. The thickness of the outergasket 54 a is 0.3 mm or more in consideration of insulation and sealingproperties. Considering the thickness of the outer gasket 54 a, if theheight of the outer flange portion 50 b is less than 0.8 mm, the outerflange portion 50 b becomes thin to a level that is difficult to securesufficient mechanical rigidity. In particular, it is more serious whenthe electrode terminal 50 is made of aluminum. Meanwhile, the height ofthe outer flange portion 50 b may be appropriately set in considerationof the space margin of the upper part of the cell. In an example, theheight of the outer flange portion 50 b may be set to 2 mm or less, or 3mm or less, or 4 mm or less, but the present disclosure is not limitedthereto.

In still another embodiment, at least a portion of the outer gasket 54 amay be exposed to the outside of the outer flange portion 50 b of theelectrode terminal 50. The outer gasket 54 a is in order to insulate theelectrode terminal 50 and the outer surface 52 a having the oppositepolarity to the electrode terminal 50 from each other. For electricalinsulation of the electrode terminal 50 and the outer surface 52 a, theexposure width (G) of the outer gasket 54 a may be 0.1 mm to 1 mm. Ifthe exposure width (G) is smaller than 0.1 mm, the electrical insulationof the electrode terminal 50 and the outer surface 42 a on a plane maybe broken when high c-rate charge/discharge of 300 A or more isperformed. In addition, if the exposure width (G) exceeds 1 mm, theelectrical insulation effect is not further increased, but rather thearea of the outer surface 42 a used as an area of the negative electrodeis reduced, so the contact area of a component (e.g., a bus bar) usedfor electrical connection is reduced.

In still another embodiment, the diameter of the flat portion 50 d ofthe electrode terminal 50 may be determined in consideration of weldingstrength between the current collecting plate and the flat portion 50 d.The tensile force of the welding portion between the flat portion 50 dand the current collecting plate may be at least 2 kgf or more, or 5 kgfor more, or 6 kgf or more, or 7 kgf or more, or 8 kgf or more, or 9 kgfor more, or 10 kgf or more. It is desirable to increase the tensileforce of the welding portion as much as possible within an allowablerange by selecting the welding method in a best way.

Referring to FIG. 6c , in order to satisfy the tensile force conditionof the welding portion, the diameter of the welding pattern Wp formed onthe flat portion 50 d may be at least 2 mm. When the area (S) of thewelding pattern Wp appearing on the surface of the welding portion isconverted into an area (πr²) of a circle, the diameter of the weldingpattern Wp may be defined as a converted diameter (2*(S/π)^(0.5)) of thecorresponding circle. The welding pattern Wp may be continuous ordiscontinuous. When the welding pattern Wp is not a circle, theconverted diameter may be determined from a maximum value amongdistances between a center of the flat portion 50 d and an outerboundary of the welding pattern Wp.

The flat portion 50 d of the electrode terminal 50 corresponds to aweldable region. The diameter of the weldable region may be 3 mm and 14mm. If the diameter of the weldable region is less than 3 mm, it isdifficult to secure a welding pattern with a diameter of 2 mm or more.In particular, when forming the welding pattern using laser welding, itis difficult to secure a welding pattern having a diameter of 2 mm ormore due to laser beam interference. If the diameter of the weldableregion exceeds 14 mm, the diameter of the outer flange portion 50 b ofthe electrode terminal 50 becomes too large, and thus it is difficult tosufficiently secure the area of the outer surface 52 a of the batterycan bottom 52 to be used as the negative electrode region.

Considering the diameter condition of the welding pattern and thediameter condition of the weldable region, the ratio of the area of thewelding pattern to the area of the weldable region required to secure atensile force of the welding portion of at least 2 kgf or more ispreferably 2.04% (π1²/π7²) to 44.4% (π1²/π1.5²).

In another embodiment, the radius (R1) from the center of the bodyportion 50 a to the edge of the outer flange portion 50 b may be 10 to70% of the radius (R2) of the bottom 52 of the battery can 51.

If R1 is small, when wiring a component (a bus bar) used for electricconnection of the electrode terminal 50, the welding space isinsufficient. In addition, if R1 is large, the welding space decreaseswhen welding a component (a bus bar) for electric connection to theouter surface 52 a of the bottom 52 of the battery can 51 except for theelectrode terminal 50.

If the ratio R1/R2 is adjusted between 10 and 70%, it is possible toproperly secure the welding space for the electrode terminal 50 and theouter surface 52 a of the bottom 52 of the battery can 51.

In addition, the radius (R3) from the center of the body portion 50 a ofthe electrode terminal 50 to the edge of the flat portion 50 d may be 4%to 30% of the radius (R2) of the bottom 52 of the battery can 51.

If R3 is small, the welding space becomes insufficient when welding acurrent collecting plate to the flat portion 50 d of the electrodeterminal 50, and the welding area of the electrode terminal 50decreases, thereby increasing the contact resistance. In addition, R3must be smaller than R1, and if R3 becomes larger, the thickness of theinner flange portion 50 c becomes thinner, and the strength of the innerflange portion 50 c compressing the rivet gasket 54 becomes weak, whichmay deteriorating the sealing ability of the rivet gasket 54.

If R3/R2 is adjusted between 4% to 30%, the welding process may beeasily performed by sufficiently securing the welding area between theflat portion 50 d of the electrode terminal 50 and the currentcollecting plate, and also it is possible to reduce the contactresistance of the welding region the and prevent the sealing ability ofthe rivet gasket 54 from deteriorating.

According to an embodiment of the present disclosure, the rivetingstructure of the electrode terminal 50 may be formed using a caulkingjig that moves up and down. First, a preform (not shown) of theelectrode terminal 50 is inserted into the perforation hole 53 formed inthe bottom 52 of the battery can 51 by interposing the rivet gasket 54.The preform refers to an electrode terminal before being riveted.

Next, the caulking jig is inserted into the inner space of battery can51. The caulking jig has a groove and a protrusion corresponding to thefinal shape of the electrode terminal 50 on the surface opposite thepreform in order to form the electrode terminal 50 by riveting thepreform.

Next, the caulking jig is moved downward to perform press-forming to theupper portion of the preform, so that the preform is transformed into ariveted electrode terminal 50.

While the preform is pressed by the caulking jig, the outer gasket 54 ainterposed between the outer flange portion 50 b and the outer surface52 a of the bottom 52 of the battery can 51 is elastically compressed sothat its thickness decreases. In addition, as the region of the innergasket 54 b interposed between the inner edge 56 of the perforation hole53 and the preform is elastically compressed by the inner flange portion50 c, the thickness of the region is further reduced than other regions.In particular, the region where the thickness of the inner gasket 54 bis intensively reduced is indicated by a dotted circle in FIG. 6a .Accordingly, the sealing and airtightness between the riveted electrodeterminal 50 and the battery can 51 are significantly improved.

Preferably, the rivet gasket 54 is compressed sufficiently to secure adesired sealing strength without being physically damaged in the processof riveting the preform.

Preferably, the compression ratio of the rivet gasket 54 may be 30% to90%. The minimum compression ratio (30%) corresponds to a compressionratio of a minimum level to ensure the sealing property of the electrodeterminal 50. The maximum compression ratio (90%) corresponds to acompression ratio of a maximum level that can be achieved withoutphysically damaging the rivet gasket 54.

In one example, when the rivet gasket 54 is made of polybutyleneterephthalate, it is preferable that the rivet gasket 54 has acompression ratio of 50% or more at the point where the rivet gasket 54is compressed to a minimum thickness. The compression ratio is a ratioof thickness change before and after compression with respect to thethickness before compression.

Preferably, the compression ratio is determined for the inner gasket 54b. That is, the compression ratio may be defined as the ratio of thethickness change at a maximum compression point compared to thethickness before compression of the inner gasket 54 b. Hereinafter, thisis also applied identically. The thickness of the inner gasket 54 bbefore compression may be uniform, and a maximum compression point mayexist near the inner edge 56.

In another example, when the rivet gasket 54 is made ofpolyfluoroethylene, it is preferable that the rivet gasket 54 has acompression ratio of 60% or more at the point where the rivet gasket 54is compressed to a minimum thickness. Preferably, the compression ratiois determined for the inner gasket 54 b.

In still another example, when the rivet gasket 54 is made ofpolypropylene, it is preferable that the rivet gasket 54 has acompression ratio of 60% or more at the point where the rivet gasket 54is compressed to a minimum thickness. Preferably, the compression ratiois determined for the inner gasket 54 b.

Preferably, press-forming may be performed in multiple stages to theupper portion of the preform by vertically moving the caulking jig atleast two times. That is, the preform may be deformed several times byperforming press-forming in multiple stages. At this time, the pressureapplied to the caulking jig may be increased step by step. In this way,the stress applied to the preform is dispersed several times, therebypreventing the rivet gasket 54 from being damaged during the caulkingprocess. In particular, when the region of the inner gasket 54 binterposed between the inner edge 56 of the perforation hole 53 and thepreform is intensively compressed by the inner flange portion 50 c, thedamage to the gasket is minimized by performing press-forming inmultiple stages.

After the press-forming is completely performed to the preform using thecaulking jig, if the caulking jig is separated from the battery can 51,the riveting structure of the electrode terminal 50 according to anembodiment of the present disclosure may be obtained as shown in FIG. 6a.

According to the above embodiment, the caulking jig performspress-forming to the upper portion of the preform by vertical movinginside the battery can 51. In some cases, a rotary jig used in the priorart may be used for performing press-forming to the preform.

However, the rotary jig rotates in a state of being inclined at apredetermined angle with respect to the central axis of the battery can51. Therefore, the rotary jig with a large rotation radius may interferewith the inner wall of the battery can 51. In addition, if the batterycan 51 has a large depth, the length of the rotary jig is alsoincreased. In this case, as the rotation radius of the end of the rotaryjig increases, press-forming may not be performed properly to thepreform. Therefore, it is more effective to perform press-forming usinga caulking jig rather than using a rotary jig.

Meanwhile, the electrode terminal 50 may have various structuresdepending on the design of the preform and/or the caulking jig and/orthe rivet gasket 54 and the magnitude of the pressure applied to thepreform during the caulking process.

FIG. 6b is a partially enlarged sectional view showing the structure ofan electrode terminals 50′ according to another embodiment of thepresent disclosure.

Referring to FIG. 6b , the electrode terminal 50′ according to anotherembodiment has a structure in which the inner flange portion 50 c isriveted to be substantially parallel to the inner surface 52 b of thebottom 52 of the battery can 51. Therefore, the angle formed by thesurface of the inner flange portion 50 c opposite to the inner surface52 b of the bottom 52 of the battery can 51 with the inner surface 52 bis substantially close to 0, and the height (H3) of the inner flangeportion 53 c is less than the height (H2) of the inner gasket 54 b. Inaddition, the inner edge 57 of the perforation hole 53 has an arc shapewith a predetermined curvature. In addition, the sidewall of the edge ofthe flat portion 50 d has a structure inclined toward the flat portion50 d.

Preferably, the thickness of the inner gasket 54 b may graduallydecrease upward, decrease to the minimum thickness near the end of theinner flange portion 53 c, and then slightly increase toward theuppermost end. The compression structure of this inner gasket 54 b mayfurther improve the sealing properties of the electrode terminal 50′.The compression ratio of the inner gasket 54 b can be calculated at theminimum thickness point near the end of the inner flange portion 53 c.

Preferably, the riveting structure of the electrode terminal 50, 50′according to the embodiments of the present disclosure described abovemay be applied to a cylindrical battery cell having a form factorgreater than 21700.

Recently, as the cylindrical battery cell is applied to an electricvehicle, the form factor of the cylindrical battery cell is increasingcompared to the conventional form factor of 18650, 21700, and the like.An increase in the form factor leads to an increase in energy density,an increase in safety against thermal runaway, and an improvement incooling efficiency.

In addition, as will be explained later, electrical wiring may beperformed at one side of the cylindrical battery cell to which theriveting structure of the electrode terminal 50, 50′ is applied. Inaddition, the electrode terminal 50, 50′ with a riveting structure has alarge sectional area and low resistance, so it is very suitable forrapid charging.

Preferably, the cylindrical battery cell to which the structure of theelectrode terminal 50, 50′ of the present disclosure is applied may havea form factor ratio (defined as a value obtained by dividing thediameter of the cylindrical battery cell by height, namely a ratio ofdiameter (Φ) to height (H)) is greater than about 0.4.

Here, the form factor means a value indicating the diameter and heightof a cylindrical battery cell. The cylindrical battery cell according toan embodiment of the present disclosure may be, for example, a 46110cell, a 48750 cell, a 48110 cell, a 48800 cell, or a 46800 cell. In thenumerical value representing the form factor, first two numbers indicatethe diameter of the cell, next two numbers indicate the height of thecell, and the last number “0” indicates that the cross-section of thecell is circular. If the height of the cell exceeds 100 mm, the lastnumber 0 can be omitted because a 3-digit number is needed to indicatethe height of the cell.

A battery cell according to an embodiment of the present disclosure maybe a cylindrical battery cell having an approximately cylindrical shape,whose diameter is approximately 46 mm, height is approximately 110 mm,and form factor ratio is 0.418.

A battery cell according to another embodiment may be a cylindricalbattery cell having a substantially cylindrical shape, whose diameter isabout 48 mm, height is about 75 mm, and form factor ratio is 0.640.

A battery cell according to still another embodiment may be acylindrical battery cell having an approximately cylindrical shape,whose diameter is approximately 48 mm, height is approximately 110 mm,and form factor ratio is 0.418.

A battery cell according to still another embodiment may be acylindrical battery cell having an approximately cylindrical shape,whose diameter is approximately 48 mm, height is approximately 80 mm,and form factor ratio is 0.600.

A battery cell according to still another embodiment may be acylindrical battery cell having an approximately cylindrical shape,whose diameter is approximately 46 mm, height is approximately 80 mm,and form factor ratio is 0.575.

Conventionally, battery cells having a form factor ratio of about 0.4 orless have been used. That is, conventionally, for example, 18650 cell,21700 cell, etc. were used. The 18650 cell has a diameter ofapproximately 18 mm, height of approximately 65 mm, and a form factorratio of 0.277. The 21700 cell has a diameter of approximately 21 mm, aheight of approximately 70 mm, and a form factor ratio of 0.300.

FIG. 7a is a sectional view showing a cylindrical battery cell 70according to an embodiment of the present disclosure, taken along alongitudinal direction (Y).

Referring to FIG. 7a , the cylindrical battery cell 70 according to theembodiment includes a jelly-roll type electrode assembly 71 in which afirst electrode plate and a second electrode plate having a sheet shapeare wound with a separator interposed therebetween so that an uncoatedportion 72 of the first electrode plate is exposed at a lower portionand an uncoated portion 73 of the second electrode plate is exposed atan upper portion.

In an embodiment, the first electrode plate may be a negative electrodeplate and the second electrode plate may be a positive electrode plate,or vice versa.

The method of winding the electrode assembly 71 is substantially thesame as the method of winding the electrode assembly used inmanufacturing the conventional tab-less cylindrical battery celldescribed with reference to FIG. 2.

In depicting the electrode assembly 71, only the uncoated portions 72,73 extending to be exposed to the outside of the separator areillustrated in detail, and the winding structure of the first electrodeplate, the second electrode plate and the separator is not illustratedin detail.

The cylindrical battery cell 70 also includes a cylindrical battery can51 that accommodates the electrode assembly 71 and is electricallyconnected to the uncoated portion 72 of the first electrode plate.

Preferably, one side (lower portion) of the battery can 51 is open. Inaddition, the bottom 52 of the battery can 51 has a structure in whichthe electrode terminal 50 is riveted to the perforation hole 53 througha caulking process.

Specifically, the electrode terminal 50 may include a body portion 50 ainserted into the perforation hole 53, an outer flange portion 50 bextending along the outer surface 52 a from the circumference of oneside of the body portion 50 a exposed through the outer surface 52 a ofthe bottom 52 of the battery can 51, an inner flange portion 50 cextending toward the inner surface 52 b from the circumference of theother side of the body portion 50 a exposed through the inner surface 52b of the bottom 52 of the battery can 51, and a flat portion 50 dprovided on the second side of the body portion 50 a.

The electrode terminal 50 may be replaced with the electrode terminal50′ shown in FIG. 6 b.

The cylindrical battery cell 70 may also include a rivet gasket 54interposed between the electrode terminal 50 and the battery can 51.

The cylindrical battery cell 70 may also include a sealing body 74 thatseals the open end of the battery can 51 to be insulated from thebattery can 51. Preferably, the sealing body 74 may include a cap plate74 a having no polarity and a sealing gasket 74 b interposed between anedge of the cap plate 74 a and the open end of the battery can 51.

The cap plate 74 a may be made of a conductive metal material such asaluminum, steel, nickel or the like. In addition, the sealing gasket 74b may be made of polypropylene, polybutylene terephthalate, polyethylenefluoride, or the like having insulation and elasticity. However, thepresent disclosure is not limited by the materials of the cap plate 74 aand the sealing gasket 74 b.

The cap plate 74 a may include a vent notch 77 that ruptures when thepressure inside the battery can 51 exceeds a threshold. The vent notch77 may be formed at both sides of the cap plate 74 a. The vent notch 77may form a continuous or discontinuous circular pattern, a straightpattern or any other pattern on the surface of the cap plate 74 a. Thedepth and width of the vent notch 77 may be set such that the vent notch77 is ruptured when the pressure inside the battery can 51 is in therange of 15 kgf/cm² to 35 kgf/cm².

The battery can 51 may include a crimping portion 75 that is extendedand bent into the inside of the battery can 51 to surround and fix theedge of the cap plate 74 a together with the sealing gasket 74 b inorder to fix the sealing body 74 to the battery can 51.

Preferably, the lower surface of the cap plate 74 a may be located abovethe lower end of the crimping portion 75. Then, a vent space is formedbelow the cap plate 74 a, so that when the vent notch 77 is ruptured,the gas can be smoothly discharged.

The battery can 51 may also include a beading portion 76 pressed-in intothe battery can 51 in a region adjacent the open end thereof. Thebeading portion 76 supports the edge of the sealing body 74,particularly the outer circumferential surface of the sealing gasket 74b, when the sealing body 74 is fixed by the crimping portion 75.

The cylindrical battery cell 70 may further include a first currentcollecting plate 78 welded to the uncoated portion 72 of the firstelectrode plate. The first current collecting plate 78 is made of aconductive metal material such as aluminum, steel, nickel or the like.Preferably, at least a portion 78 a of the edge of the first currentcollecting plate 78 not in contact with the uncoated portion 72 of thefirst electrode plate may be interposed between the beading portion 76and the sealing gasket 74 b and fixed by the crimping portion 75.Optionally, at least a portion 78 a of the edge of the first currentcollecting plate 78 may be fixed to the inner circumference 76 a of thebeading portion 76 adjacent to the crimping portion 75 by a laserwelding, a spot welding, an ultrasonic welding or the like.

The cylindrical battery cell 70 may also include a second currentcollecting plate 79 that is welded to the uncoated portion 73 of thesecond electrode plate. Preferably, at least a portion of the secondcurrent collecting plate 79, for example a central portion 79 a thereof,may be welded to the flat portion 50 d of the electrode terminal 50.

Preferably, when the second current collecting plate 79 is welded, awelding tool may be inserted through the cavity 80 in the core of theelectrode assembly 71 to reach a welding point of the second currentcollecting plate 79. In addition, when the second current collectingplate 79 is welded to the flat portion 50 d of the electrode terminal50, since the electrode terminal 50 supports the welding region of thesecond current collecting plate 79, it is possible to improve thewelding quality by applying a strong pressure to the welding region. Inaddition, since the flat portion 50 d of the electrode terminal 50 has alarge area, a wide welding region may also be secured. Accordingly, thecontact resistance of the welding region is lowered, thereby loweringthe inner resistance of the cylindrical battery cell 70. Theface-to-face welding structure of the riveted electrode terminal 50 andthe second current collecting plate 79 is very useful for rapid chargingusing high C-rate current. This is because the current density per unitarea may be lowered in the cross section in a direction in which thecurrent flows and thus the amount of heat generated in the current pathmay be lowered than that of the prior art.

When welding the flat portion 50 d of the electrode terminal 50 and thesecond current collecting plate 79, any one of laser welding, ultrasonicwelding, spot welding, and resistance welding may be used.

In one example, when the flat portion 50 d and the second currentcollecting plate 79 are laser-welded in a continuous or discontinuousline in the form of an arc pattern, the diameter of the arc weldingpattern is 2 mm or more, preferably 4 mm or more. When the diameter ofthe arc welding pattern satisfies the corresponding conditions, it ispossible to increase the tensile force of the welding portion to 2 kgfor above, thereby securing sufficient welding strength.

In another example, when the flat portion 50 d and the second currentcollecting plate 79 are ultrasonic-welded in a circular pattern, thediameter of the circular welding pattern is preferably 2 mm or more.When the diameter of the circular welding pattern satisfies thecorresponding conditions, it is possible to increase the tensile forceof the welding portion to 2 kgf or above, thereby securing sufficientwelding strength. The diameter of the flat portion 50 d corresponding tothe weldable region may be adjusted in the range of 3 mm to 14 mm. Ifthe radius of the flat portion 50 d is less than 3 mm, it is difficultto form a welding pattern with a diameter of 2 mm or more using a laserwelding tool, an ultrasonic welding tool, or the like. In addition, ifthe radius of the flat portion 50 d exceeds 14 mm, the size of theelectrode terminal 50 becomes excessively large, and the area occupiedby the outer surface 52 a of the bottom 52 of the battery can 51 isreduced, so that it is difficult to connect an electrical connectioncomponent (a bus bar) through the outer surface 52 a.

Preferably, since the diameter of the welding pattern for securing thewelding portion tensile force to 2 kgf or more is 2 mm or more and thediameter of the weldable region is 3 mm to 14 mm, the area ratio of thewelding pattern to the area of the weldable region may be2.04(100*π1²/π7²)% to 44.4(100*π1²/π1.5²)%.

The cylindrical battery cell 70 may further include an insulator 80. Theinsulator 80 may be interposed between the second current collectingplate 79 and the inner surface 52 a of the bottom 52 of the battery can51, and between the inner circumference 51 a of the sidewall of thebattery can 51 and the electrode assembly 71.

Preferably, the insulator 80 may have a welding hole 80 a that exposesthe flat portion 50 d of the electrode terminal 50 toward the secondcurrent collecting plate 79. In addition, the welding hole 80 a mayexpose the inner flange portion 50 c and the inner gasket 54 b togetherwith the flat portion 50 d of the electrode terminal.

Preferably, the insulator 80 may cover the surface of the second currentcollecting plate 79 and one (upper) edge of the electrode assembly 71.By doing so, it is possible to prevent the second current collectingplate 79 having a polarity different from that of the battery can 51from contacting the uncoated portion 73 of the second electrode plate.

Preferably, the insulator 80 is made of an insulating resin, and mayinclude an upper plate 80 b and a side sleeve 80 c. In one example, theupper plate 80 b and the side sleeve 80 c may be integrally formed byinjection molding. Alternatively, the side sleeve 80 c may be replacedwith an insulation tape or the like. The insulation tape may cover theouter edge of the second current collecting plate 79 together with theuncoated portion 73 of the second electrode plate exposed through theouter circumference of the electrode assembly 71.

Preferably, the inner surface 52 b of the insulator 80 and the bottom 52of the battery can 51 may be in close contact with each other as shownin FIG. 7b . Here, ‘close contact’ means that there is no space (gap)that is visually confirmed. In order to eliminate the space (gap), thedistance from the inner surface 52 b of the bottom 52 of the battery can51 to the flat portion 50 d of the electrode terminal 50 may be equal toor slightly smaller than the thickness of the insulator 80.

Preferably, the uncoated portions 72, 73 of the first electrode plateand/or the second electrode plate may be bent in a radial direction, forexample from the outer circumference of the electrode assembly 71 to thecore, to form bent surfaces at the upper and lower portions of theelectrode assembly 71. In addition, the first current collecting plate78 may be welded to the bent surface formed by bending the uncoatedportion 72 of the first electrode plate, and the second currentcollecting plate 79 may be welded to the bent surface formed by bendingthe uncoated portion 73 of the second electrode plate.

In order to relieve the stress generated when the uncoated portions 72,73 are bent, the first electrode plate and/or the second electrode platemay have an improved structure different from that of the conventionalelectrode plate (see FIG. 1).

FIG. 8 is a plan view exemplarily showing a structure of an electrodeplate 90 according to a preferred embodiment of the present disclosure.

Referring to FIG. 8, the electrode plate 90 has a sheet-shaped currentcollector 91 made of a conductive material foil, an active materiallayer 92 formed on at least one surface of the current collector 91, andan uncoated portion 93 formed at a long side end of the currentcollector 91 and not coated with an active material.

Preferably, the uncoated portion 93 may include a plurality of notchedsegments 93 a. The plurality of segments 93 a constitute a plurality ofgroups, and the segments 93 a included in each group may have the sameheight (length in the Y direction) and/or the same width (length in theX direction) and/or the same separation pitch. The number of segments 93a belonging to each group may be increased or decreased than shown. Thesegment 93 a has a shape of a geometric figure in which at least onelinear line and/or at least one curve are combined. Preferably, thesegment 93 a may have a trapezoidal shape, which may be changed into arectangular, parallelogram, semicircular, semi-elliptical shape, or thelike as desired.

Preferably, the height of the segment 93 a may be increased stepwisealong one direction parallel to the winding direction of the electrodeassembly, for example from the core to the outer circumference. Inaddition, a core-side uncoated portion 93′ adjacent to the core may notinclude the segment 93 a, and the height of the core-side uncoatedportion 93′ may be smaller than that of other uncoated portion regions.Also, an outer circumferential uncoated portion 93″ adjacent to theouter circumferential may not include the segment 93 a, and the heightof the outer circumferential uncoated portion 93″ may be smaller thanthat of other uncoated portion regions.

Optionally, the electrode plate 90 may include an insulating coatinglayer 94 for covering the boundary between the active material layer 92and the uncoated portion 93. The insulating coating layer 94 includes aninsulating polymer resin, and may optionally include an inorganic fillerfurther. The insulating coating layer 94 prevents the end of the activematerial layer 92 from coming into contact with the opposite-polarityactive material layer opposite thereto through the separator, and servesto structurally support the bending of the segment 93 a. To this end,when the electrode plate 90 is wound into an electrode assembly, it ispreferable that the insulating coating layer 94 is at least partiallyexposed from the separator to the outside.

FIG. 9 is a sectional view showing an electrode assembly 100 in which asegment structure of an uncoated portion of the electrode plate 90according to an embodiment of the present disclosure is applied to thefirst electrode plate and the second electrode plate, taken along thelongitudinal direction (Y).

Referring to FIG. 9, the electrode assembly 100 may be manufactured bythe winding method described with reference to FIG. 2. For convenienceof explanation, the protruding structure of the uncoated portions 72, 73extending out of the separator is illustrated in detail, and the windingstructure of the first electrode plate, the second electrode plate andthe separator is not illustrated in detail. The uncoated portion 72protruding downward extends from the first electrode plate, and theuncoated portion 73 protruding upward extends from the second electrodeplate.

The pattern in which the heights of the uncoated portions 72, 73 changeis schematically shown. That is, the heights of the uncoated portions72, 73 may vary irregularly depending on the position at which thecross-section is cut. For example, when the side portion of thetrapezoidal segment 93 a is cut, the height of the uncoated portion atthe cross section is lower than the height of the segment 93 a.Accordingly, it should be understood that the heights of the uncoatedportions 72, 73 depicted in the drawing showing the cross-section of theelectrode assembly 100 correspond to the average of the heights of theuncoated portions included in each winding turn.

The uncoated portions 72, 73 may be bent along the radial direction ofthe electrode assembly 100, for example from the outer circumference tothe core, as shown in FIGS. 10a and 10b . In FIG. 9, the bent portion101 is indicated by a dotted line box. When the uncoated portions 72, 73are bent, bent surfaces 102 are formed at the upper and lower portionsof the electrode assembly 100 as the segments adjacent to each other ina radius direction overlap each other in multiple layers. At this time,the core-side uncoated portion 93′ (see FIG. 8) is not bent due to itslow height, and the height (h) of the segment bent at the innermost sideis less than or equal to the radius-direction length (r) of the windingregion formed by the core-side uncoated portion 93′ with no segmentstructure. Therefore, the cavity 80 in the core of the electrodeassembly 100 is not closed by the bent segments. If the cavity 80 is notclosed, there is no difficulty in the electrolyte injection process, andthe electrolyte injection efficiency is improved. In addition, theelectrode terminal 50 and the second current collecting plate 79 may beeasily welded by inserting a welding tool through the cavity 80.

In the cylindrical battery cell 70 according to the embodiment of thepresent disclosure, the cap plate 74 a of the sealing body 74 has nopolarity. Instead, the first current collecting plate 78 is connected tothe sidewall of the battery can 51, so that the outer surface 52 a ofthe bottom 52 of the battery can 51 has polarity opposite to theelectrode terminal 50. Therefore, when a plurality of cells are to beconnected in series and/or in parallel, wiring such as bus barconnection may be performed at the upper portion of the cylindricalbattery cell 70 using the electrode terminal 50 and the outer surface 52a of the bottom 52 of the battery can 51. Through this, the energydensity may be improved by increasing the number of cells that can bemounted in the same space, and the electric wiring work may be performedeasily.

FIG. 11 is a diagram showing a state in which the cylindrical batterycells 70 according to an embodiment of the present disclosure areelectrically connected using a bus bar 150.

Referring to FIG. 11, the plurality of cylindrical battery cells 70 maybe connected in series and in parallel at an upper portion using the busbar 150. The number of cylindrical battery cells 70 may be increased ordecreased in consideration of the capacity of the battery pack.

In each cylindrical battery cell 70, the electrode terminal 50 may havea positive polarity, and the outer surface 52 a of the bottom 52 of thebattery can 51 may have a negative polarity, and vice versa.

Preferably, the plurality of cylindrical battery cells 70 may bearranged in a plurality of columns and rows. Columns are provided in anupper and lower direction with respect to the ground, and rows areprovided in a left and right direction with respect to the ground. Also,in order to maximize space efficiency, the cylindrical battery cells 70may be arranged in a closest packing structure. The closest packingstructure is formed when the centers of the electrode terminals 50 forman equilateral triangle when being connected to each other.

Preferably, the bus bar 150 may be disposed above the plurality ofbattery cells, more preferably between adjacent columns. Alternatively,the bus bar 150 may be disposed between adjacent rows.

Preferably, the bus bar 150 connects cells arranged in the same columnin parallel to each other, and serially connects cells arranged in twoadjacent columns to each other.

Preferably, for serial and parallel connection, the bus bar 150 mayinclude a body portion 151, a plurality of first bus bar terminals 152and a plurality of second bus bar terminals 153.

The body portion 151 may extend between electrode terminals (50) ofadjacent cylindrical battery cells 70, preferably between columns of thecylindrical battery cells 70. Alternatively, the body portion 151 mayextend along a column of cylindrical battery cells 70 and may beregularly bent like a zigzag shape.

The plurality of first bus bar terminals 152 may protrude from one sideof the body portion 151 toward the electrode terminal 50 of eachcylindrical battery cell 70 and may be electrically coupled to theelectrode terminal 50. Electrical coupling with the electrode terminal50 may be achieved through laser welding, ultrasonic welding, or thelike. In addition, the plurality of second bus bar terminals 153 mayprotrude from the other side of the body portion 151 toward the outersurface 52 a of the bottom 52 of the battery can 51 of each cylindricalbattery cell 70, and may be electrically coupled to the outer surface 52a. Electrical coupling with the outer surface 52 a may be performed bylaser welding, ultrasonic welding, or the like.

Preferably, the body portion 151, the plurality of first bus barterminals 152 and the plurality of second bus bar terminals 153 may bemade of one conductive metal plate. The metal plate may be an aluminumplate or a copper plate, but the present disclosure is not limitedthereto. In a modified example, the body portion 151, the plurality offirst bus bar terminals 152 and the plurality of second bus barterminals 153 may be manufactured as separate pieces and then coupled toeach other through welding or the like.

In the cylindrical battery cell 70 according to the present disclosure,the electrode terminal 50 having a positive polarity and the outersurface 52 a of the bottom 52 of the battery can 51 having a negativepolarity are located in the same direction, and thus the cylindricalbattery cells 70 may be electrically connected easily using the bus bar150.

In addition, since the electrode terminal 50 and the outer surface 52 aof the cylindrical battery cell 70 have a large area, the coupling areaof the bus bar 150 may be sufficiently secured to sufficiently reducethe resistance of the battery pack including the cylindrical batterycell 70.

FIG. 12a is a partially enlarged view showing an electrical connectionportion between the bus bar 150 and the cylindrical battery cell 70, andFIGS. 12b and 12c are diagrams showing the definition of variousparameters to design upper and lower limits of the diameter of theelectrode terminal 50 and the exposure width of the outer surface 52 ain consideration of the sizes of the bus bar terminals 152, 153.

Referring to FIGS. 12a, 12b and 12c , in the cylindrical battery cell70, the diameter (E₁) of the outer flange portion 50 b of the electrodeterminal 50 and the width (E₂) of the ring-shaped outer surface 52 a maybe adaptively adjusted in consideration of the dimensions of the contactareas of the bus bar terminals 152, 153.

Here, the width E2 of the outer surface 52 a is the width of the exposedsurface parallel to the surface of the electrode terminal 50.Specifically, the width E2 of the outer surface 52 a is defined as thewidth of a line segment connecting two points where a linear line (L₁)drawn in a radial direction from the center C of the electrode terminal50 intersects inner and outer boundaries of the outer surface 52 a. Thewidth E2 of the outer surface 52 a is the width of the flat exposedsurface excluding the round region existing at the edge of the bottom 52and the exposed area 54 a′ of the outer gasket 54 a.

The outer surface of the bottom 52 of the battery can 51 may be dividedinto the electrode terminal 50, the exposed area 54 a′ of the rivetgasket 54, and the round region R at the edge of the outer surface 52 awhen viewed from the top. The round region R is a processing region (seeFIGS. 7a and 7b ) for smoothly connecting the bottom 52 of the batterycan 51 and the sidewall of the battery can 51, and has a width (R_(d))on a plane.

The first bus bar terminal 152 of the bus bar 150 is branched to oneside different from the traveling direction of the body portion 151, andis electrically coupled to the electrode terminal 50. At this time, theelectrode terminal 50 and the first bus bar terminal 152 form a firstoverlapping region (hatched in the drawing) on a plane, and the firstoverlapping region has a first width (W₁). Here, the first overlappingregion is a region where the electrode terminal 50 and the first bus barterminal 152 overlap on a plane.

The first width (W₁) is defined as a maximum value among distancesbetween any two points selected in the edge of the first overlappingregion. The definition of the first width (W₁) is applied identicallywhen the first overlapping region includes the center of the electrodeterminal 50 (FIG. 12b ) and when the first overlapping region does notinclude the center of the electrode terminal 50 (FIG. 12c ). Referringto FIGS. 12b and 12c , the distance represented by W₁ corresponds to amaximum value among distances between any two points selected in theedge of the first overlapping region.

The second bus bar terminal 153 of the bus bar 150 extends in adirection opposite to the first bus bar terminal 152 based on thetraveling direction of the body portion 151, and is electrically coupledto the outer surface 52 a of the bottom 52 of the battery can 51. Atthis time, the second bus bar terminal 153 and the outer surface 52 aform a second overlapping region (hatched on the figure) on a plane, andthe second overlapping region has a second width (W₂). Here, the secondoverlapping region is a region where the outer surface 52 a and thesecond bus bar terminal 153 overlap on a plane.

The second width (W₂) is defined as a maximum value among widths betweentwo points where each linear line and the edge of the second overlappingregion meet when a plurality of linear lines (L₃) are drawn from thecenter C of the electrode terminal 50 to pass through the secondoverlapping region.

Preferably, the diameter (E₁) of the outer flange portion 50 b of theelectrode terminal 50 must be at least equal to or greater than thefirst width (W₁) of the first bus bar terminal 152. This is because thefirst overlapping region of the first bus bar terminal 152 and theelectrode terminal 50 must not deviate out of the electrode terminal 50on the plane. Also, the diameter (E₁) of the outer flange portion 50 bof the electrode terminal 50 may be increased to the maximum until thedistance between the boundary of the electrode terminal 50 and thesecond bus bar terminal 153 corresponds to the width (G) of the exposedarea 54 a′ of the outer gasket 54 a. Therefore, the maximum value of thediameter (E₁) of the outer flange portion 50 b of the electrode terminal50 is ‘D−2*Ra−2*G−2*W₂’.

Preferably, the width (E₂) of the outer surface 52 a is a factordependent on the diameter (E₁) of the outer flange portion 50 b of theelectrode terminal 50, and must be at least equal to or greater than thesecond width (W₂) of the second bus bar terminal 153. Only in this case,an overlapping region of the second bus bar terminal 153 and the outersurface 52 a may be formed. In addition, the width (E₂) of the outersurface 52 a may be increased to the maximum up to 50% of‘D−2*R_(d)−2*G-E₁’, which is a value obtained by subtracting thediameter (E₁) of the outer flange portion 50 b of the electrode terminal50, the width (2*G) of the exposed area of the outer gasket 54 a, andthe width (2*R_(d)) of the round region from the outer diameter (D) ofthe battery can 51.

In conclusion, in the cylindrical battery cell 70 according to thepresent disclosure, it is preferable that the diameter (E₁) of the outerflange portion 50 b of the electrode terminal 50 and the width (E₂) ofthe outer surface 52 a are designed to satisfy the following relationalexpression.

W ₁ ≤E ₁ ≤D−2R _(d)−2G−2W ₂

E ₂=0.5*(D−2R _(d)−2G−E ₁)

(E₁: diameter of the outer flange portion 50 b of the electrode terminal50, E₂: width of the outer surface 52 a, D: outer diameter of thebattery can 51, R_(d): width of the round region R measured on a plane,G: width of the exposed area 54 a′ of the outer gasket 54 a, W₁: widthof the first bus bar terminal 152, W₂: width of the second bus barterminal 153)

In a specific example, when D is 46 mm, W₁ and W₂ are 6 mm, G is 0.5 mm,and R is 1 mm, the diameter (E₁) of the outer flange portion 50 b of theelectrode terminal 50 is 6 mm to 31 mm, and the width (E₂) of the outersurface 52 a is 6 mm to 18.5 mm.

As another example, when D is 46 mm, W₁ and W₂ are 6 mm, G is 0.5 mm andR_(d) is 1.5 mm, the diameter (E₁) of the outer flange portion 50 b ofthe electrode terminal 50 is 6 mm to 30 mm and the width (E₂) of theouter surface 52 a is 6 mm to 18 mm.

As described above, the cylindrical battery cell 70 of the presentdisclosure has a structure in which resistance is minimized by expandinga welding area through a bent surface of the uncoated portion,multiplexing a current path by using a first current collecting plate,minimizing a current path length, and the like. The AC resistance of thecylindrical battery cell 70 measured using a resistance measuringinstrument between the electrode terminal 50 (positive-polarityterminal) and the outer surface 52 a (negative-polarity terminal) nearthe electrode terminal 50 may be about 4 milliohms (mohm) or less, whichis appropriate to quick charging.

In the present disclosure, a positive electrode active material coatedon the positive electrode plate and a negative electrode active materialcoated on the negative electrode plate may employ any active materialknown in the art without limitation.

In one example, the positive electrode active material may include analkali metal compound expressed by a general formulaA[A_(x)M_(y)]O_(2+z) (A includes at least one element among Li, Na andK; M includes at least one element selected from is Ni, Co, Mn, Ca, Mg,Al, Ti, Si, Fe, Mo, V, Zr, Zn, Cu, Al, Mo, Sc, Zr, Ru, and Cr; x≥0,1≤x+y≤2, −0.1≤z≤2; and the stoichiometric coefficients x, y and z areselected so that the compound maintains electrical neutrality).

In another example, the positive electrode active material may be analkali metal compound xLiM¹O₂−(1−x)Li₂M²O₃ disclosed in U.S. Pat. Nos.6,677,082, 6,680,143, et al., wherein M¹ includes at least one elementhaving an average oxidation state 3; M² includes at least one elementhaving an average oxidation state 4; and 0≤x≤1).

In still another example, the positive electrode active material may belithium metal phosphate expressed by a general formula Li_(a)M¹_(x)Fe_(1-x)M² _(y)P_(1-y)M³ _(z)O_(4-z) (M¹ includes at least oneelement selected from the Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mgand Al; M² includes at least one element selected from Ti, Si, Mn, Co,Fe, V, Cr, Mo, Ni, Nd, Al, Mg, Al, As, Sb, Si, Ge, V and S; M³ includesa halogen element optionally including F; 0<a≤2, 0≤x≤1, 0≤y<1, 0≤z<1;the stoichiometric coefficients a, x, y and z are selected so that thecompound maintains electrical neutrality), or Li₃M₂(PO₄)₃ (M includes atleast one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Al,Mg and Al).

Preferably, the positive electrode active material may include primaryparticles and/or secondary particles in which the primary particles areaggregated.

In one example, the negative electrode active material may employ carbonmaterial, lithium metal or lithium metal compound, silicon or siliconcompound, tin or tin compound, or the like. Metal oxides such as TiO₂and SnO₂ with a potential of less than 2V may also be used as thenegative electrode active material. As the carbon material,low-crystalline carbon and/or high-crystalline carbon may be used.

The separator may employ a porous polymer film, for example, a porouspolymer film made of a polyolefin-based polymer such as ethylenehomopolymer, propylene homopolymer, ethylene/butene copolymer,ethylene/hexene copolymer, ethylene/methacrylate copolymer, or the like,or laminates thereof. As another example, the separator may employ acommon porous nonwoven fabric, for example, a nonwoven fabric made ofhigh melting point glass fiber, polyethylene terephthalate fiber, or thelike.

A coating layer of inorganic particles may be included in at least onesurface of the separator. It is also possible that the separator itselfis made of a coating layer of inorganic particles. Particles in thecoating layer may be coupled with a binder so that an interstitialvolume exists between adjacent particles.

The inorganic particles may be made of an inorganic material having adielectric constant of 5 or more. As a non-limiting example, theinorganic particles may include at least one material selected from thegroup consisting of Pb(Zr,Ti)O₃ (PZT), Pb_(1-x)La_(x)Zr_(1-y)Ti_(y)O₃(PLZT), PB(Mg₃Nb_(2/3))O₃—PbTiO₃ (PMN-PT), BaTiO₃, hafnia (HfO₂),SrTiO₃, TiO₂, Al₂O₃, ZrO₂, SnO₂, CeO₂, MgO, CaO, ZnO and Y₂O₃.

The electrolyte may be a salt having a structure like A+B⁻. Here, A⁺includes an alkali metal cation such as Li⁺, Na⁺, or K⁺, or acombination thereof and B⁻ includes at least one anion selected from thegroup consisting of F⁻, Cl⁻, Br⁻, I⁻, NO₃ ⁻, N(CN)₂ ⁻, BF₄ ⁻, ClO₄ ⁻,AlO₄ ⁻, AlCl₄ ⁻, PF₆ ⁻, SbF₆ ⁻, AsF₆ ⁻, BF₂C₂O₄ ⁻, BC₄O₈ ⁻, (CF₃)₂PF₄ ⁻,(CF₃)₃PF₃ ⁻, (CF₃)₄PF₂ ⁻, (CF₃)₅PF⁻, (CF₃)₆P⁻, CF₃SO₃, C₄F₉SO₃,CF₃CF₂SO₃ ⁻, (CF₃SO₂)₂N⁻, (FSO₂)₂N⁻, CF₃CF₂(CF₃)₂CO⁻, (CF₃SO₂)₂CH⁻,(SF₅)₃C⁻, (CF₃SO₂)₃C⁻, CF₃(CF₂)₇SO₃ ⁻, CF₃CO₂ ⁻, CH₃CO₂ ⁻, SCN⁻ and(CF₃CF₂SO₂)₂N⁻.

The electrolyte may also be dissolved in an organic solvent. The organicsolvent may employ propylene carbonate (PC), ethylene carbonate (EC),diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate(DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane,diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethylmethyl carbonate (EMC), γ-butyrolactone, or a mixture thereof.

The cylindrical battery cell 70 according to the above embodiment may beused to manufacture a battery pack.

FIG. 13 is a diagram schematically showing a battery pack according toan embodiment of the present disclosure.

Referring to FIG. 13, a battery pack 200 according to an embodiment ofthe present disclosure includes an aggregate in which cylindricalbattery cells 201 are electrically connected, and a pack housing 202 foraccommodating the aggregate. The cylindrical battery cell 201 is thebattery cell according to the above embodiment. In the drawing,components such as a bus bar, a cooling unit, and an external terminalfor electrical connection of the cylindrical battery cells 201 are notdepicted for convenience of illustration.

The battery pack 200 may be mounted to a vehicle. The vehicle may be,for example, an electric vehicle, a hybrid electric vehicle, or aplug-in hybrid vehicle. The vehicle includes a four-wheeled vehicle or atwo-wheeled vehicle.

FIG. 14 is a diagram for illustrating a vehicle including the batterypack 200 of FIG. 13.

Referring to FIG. 14, a vehicle V according to an embodiment of thepresent disclosure includes the battery pack 200 according to anembodiment of the present disclosure. The vehicle V operates byreceiving power from the battery pack 200 according to an embodiment ofthe present disclosure.

The present disclosure has been described in detail. However, it shouldbe understood that the detailed description and specific examples, whileindicating preferred embodiments of the disclosure, are given by way ofillustration only, since various changes and modifications within thescope of the disclosure will become apparent to those skilled in the artfrom this detailed description.

What is claimed is:
 1. A riveting structure of an electrode terminal fora battery, comprising: a battery housing having a bottom; an electrodeterminal riveted through a hole formed in the bottom of the batteryhousing; and a gasket between the electrode terminal and the batteryhousing, wherein the electrode terminal includes: a body portioninserted into the hole; an outer flange portion extending along an outersurface of the bottom of the battery housing from a first side of thebody portion exposed through the outer surface; an inner flange portionextending toward an inner surface of the bottom of the battery housingfrom a second side of the body portion exposed through the innersurface; and a flat portion on the second side of the body portion. 2.The riveting structure of an electrode terminal according to claim 1,wherein the flat portion is parallel with the inner surface of thebottom of the battery housing.
 3. The riveting structure of an electrodeterminal according to claim 1, wherein an angle between the inner flangeportion and the inner surface of the bottom of the battery housing is ina range of 0° to 60°.
 4. The riveting structure of an electrode terminalaccording to claim 1, wherein a recess is provided between the innerflange portion and the flat portion.
 5. The riveting structure of anelectrode terminal according to claim 4, wherein the recess has anasymmetric cross section.
 6. The riveting structure of an electrodeterminal according to claim 5, wherein the asymmetric cross section ofthe recess includes a sidewall and an inclined surface of the innerflange portion connected to an end of the sidewall.
 7. The rivetingstructure of an electrode terminal according to claim 6, wherein thesidewall is perpendicular to the inner surface of the bottom of thebattery housing.
 8. The riveting structure of an electrode terminalaccording to claim 6, wherein the sidewall is inclined toward the flatportion.
 9. The riveting structure of an electrode terminal according toclaim 1, wherein the inner flange portion has a gradually decreasingthickness in a direction extending away from the body portion.
 10. Theriveting structure of an electrode terminal according to claim 1,wherein the gasket includes: an outer gasket between the outer flangeportion and the outer surface of the bottom of the battery housing, andan inner gasket between the inner flange portion and the inner surfaceof the bottom of the battery housing, wherein the inner gasket has avarying thickness.
 11. The riveting structure of an electrode terminalaccording to claim 10, wherein a region of the inner gasket between aninner edge of the inner surface of the bottom of the battery housing andthe inner flange portion has a relatively smaller thickness than aremainder of the inner gasket.
 12. The riveting structure of anelectrode terminal according to claim 10, wherein a region of the innergasket between the battery housing and the body portion has a graduallydecreasing thickness in a direction extending from the outer flangeportion.
 13. The riveting structure of an electrode terminal accordingto claim 10, wherein a region of the inner gasket between the innersurface of the bottom of the battery housing and a region near an end ofthe inner flange portion has a smaller thickness than a remainder of theinner gasket.
 14. The riveting structure of an electrode terminalaccording to claim 10, wherein the inner edge of the hole includes afacing surface that faces the inner flange portion.
 15. The rivetingstructure of an electrode terminal according to claim 10, wherein theinner gasket extends outwardly further than the inner flange portion.16. The riveting structure of an electrode terminal according to claim10, wherein a height of the flat portion is equal to or larger than aheight of an end of the inner gasket based on the inner surface of thebottom of the battery housing.
 17. The riveting structure of anelectrode terminal according to claim 1, wherein a height of the flatportion is equal to or larger than a height of the inner flange portionbased on the inner surface of the bottom of the battery housing.
 18. Theriveting structure of an electrode terminal according to claim 10,wherein a height of the inner flange portion is larger than a height ofan end of the inner gasket based on the inner surface of the bottom ofthe battery housing.
 19. The riveting structure of an electrode terminalaccording to claim 1, wherein a height of the inner flange portion is0.5 mm to 3.0 mm based on the inner surface of the bottom of the batteryhousing.
 20. The riveting structure of an electrode terminal accordingto claim 19, wherein a height of the electrode terminal extending from alower surface of the outer flange portion to a surface of the flatportion is 4 mm to 7 mm.
 21. The riveting structure of an electrodeterminal according to claim 1, wherein a height of the outer flangeportion is 0.8 mm or more based on the outer surface of the bottom ofthe battery housing.
 22. The riveting structure of an electrode terminalaccording to claim 10, wherein at least a portion of the outer gasket isexposed to the outside of the outer flange portion, and a width of theexposed portion of the outer gasket measured in a direction parallel tothe outer surface of the bottom of the battery housing is 0.1 mm to 1mm.
 23. The riveting structure of an electrode terminal according toclaim 1, wherein a radius from a center of the body portion to an edgeof the outer flange portion is 10% to 70% of a radius of the bottom ofthe battery housing.
 24. The riveting structure of an electrode terminalaccording to claim 1, wherein a radius from a center of the body portionto an edge of the flat portion is 4% to 30% of a radius of the bottom ofthe battery housing.
 25. The riveting structure of an electrode terminalaccording to claim 10, wherein a compression ratio of the inner gasketis 30% to 90%, and wherein the compression ratio is a ratio of thicknesschange at a maximum compression point to a thickness before compressionof the gasket.
 26. The riveting structure of an electrode terminalaccording to claim 25, wherein the inner gasket includes polybutyleneterephthalate, polyethylene fluoride, or polypropylene, and wherein thecompression ratio of the inner gasket is 50% to 90%.
 27. A battery,comprising: an electrode assembly comprising a first electrode and asecond electrode wound with a separator therebetween, wherein each ofthe first electrode and the second electrode has a first portion coatedwith an active material, and a second portion, wherein the secondportion of the first electrode and the second portion of the secondelectrode are extended from opposite ends of the electrode assembly andexposed to the outside of the separator; a battery housing accommodatingthe electrode assembly and electrically connected to the firstelectrode, the battery housing having a first end with a first openingand a second end opposite the first end; an electrode terminal rivetedthrough a hole formed in the second end of the battery housing andelectrically connected to the second electrode, the electrode terminalincluding: a body portion inserted into the hole; an outer flangeportion extending along an outer surface of the second end of thebattery housing from a first side of the body portion exposed throughthe outer surface; an inner flange portion extending toward an innersurface of the second end of the battery housing from a second side ofthe body portion exposed through the inner surface; and a flat portionin the second side of the body portion; a gasket between the electrodeterminal and the battery housing; and a sealing body sealing the firstopening of the first end of the battery housing.
 28. The batteryaccording to claim 27, wherein the battery housing includes a beadingportion formed in a region adjacent to the first end of the batteryhousing which is pressed-in into the battery housing, and wherein thesealing body includes a cap having no polarity and a sealing gasketbetween an edge of the cap and the first end of the battery housing. 29.The battery according to claim 28, wherein the battery housing furtherincludes a crimping portion extended and bent into the inside of thebattery housing to surround and fix the edge of the cap together withthe sealing gasket.
 30. The battery according to claim 28, wherein thecap includes a vent notch that ruptures when a pressure inside thebattery housing exceeds a threshold pressure.
 31. The battery accordingto claim 30, wherein the vent notch is ruptured when the pressure insidethe battery housing is in a range of 15 kgf/cm² to 35 kgf/cm².
 32. Thebattery according to claim 28, further comprising: a first currentcollecting unit coupled to the second portion of the first electrode,wherein at least a part of an edge of the first current collecting unitnot in contact with the second portion of the first electrode is betweenthe beading portion and the sealing gasket and fixed by the crimpingportion.
 33. The battery according to claim 32, wherein at least a partof the edge of the first current collecting unit is fixed to an innercircumference of the beading portion adjacent to the crimping portion bywelding.
 34. The battery according to claim 27, further comprising: asecond current collecting unit coupled to the second portion of thesecond electrode plate, wherein at least a part of the second currentcollecting unit is coupled to the flat portion of the electrodeterminal.
 35. The battery according to claim 34, wherein the secondcurrent collecting unit and the flat portion of the electrode terminalare coupled through welding, and wherein a tensile force of a weldbetween the second current collecting unit and the flat portion of theelectrode terminal is 2 kgf or above.
 36. The battery according to claim35, wherein a diameter of a welding pattern exposed on a surface of thesecond current collecting unit is 2 mm or more.
 37. The batteryaccording to claim 27, wherein a diameter of the flat portion of theelectrode terminal is 3 mm to 14 mm.
 38. The battery according to claim35, wherein a ratio of an area of a welding pattern exposed on a surfaceof the second current collecting unit to an area of the flat portion ofthe electrode terminal is 2.04% to 44.4%.
 39. The battery according toclaim 34, further comprising: an insulator between the second currentcollecting unit and an inner surface of the second end of the batteryhousing and between an inner surface of a sidewall of the batteryhousing and the electrode assembly.
 40. The battery according to claim39, wherein the insulator has a welding hole formed to expose the flatportion of the electrode terminal toward the second current collectingunit and covers a surface of the second current collecting unit and anedge of one side of the electrode assembly.
 41. The battery according toclaim 40, wherein a height from the inner surface of the second end ofthe battery housing to the flat portion of the electrode terminal isequal to or smaller than a thickness of the insulator.
 42. The batteryaccording to claim 40, wherein the gasket includes: an outer gasketbetween the outer flange portion and the outer surface of the second endof the battery housing; and an inner gasket between the inner flangeportion and the inner surface of the second end of the battery housing.43. The battery according to claim 42, wherein an end of the innergasket is exposed to the outside of the inner flange portion.
 44. Thebattery according to claim 42, wherein the welding hole exposes the flatportion of the electrode terminal and the inner flange portion.
 45. Thebattery according to claim 43, wherein the welding hole exposes the flatportion of the electrode terminal, the inner flange portion and theinner gasket.
 46. The battery according to claim 27, wherein a first busbar terminal is electrically coupled to a surface of the electrodeterminal, and a second bus bar terminal is electrically coupled to theouter surface of the second end of the battery housing.
 47. The batteryaccording to claim 46, wherein the first bus bar terminal overlaps withthe electrode terminal on a plane to form a first overlapping region,and the second bus bar terminal overlaps with the outer surface of thesecond end of the battery housing to form a second overlapping region,and wherein a diameter of the electrode terminal and a width of theouter surface of the second end of the battery housing satisfy thefollowing relational expression,W ₁ ≤E ₁ ≤D−2R _(d)−2G−2W ₂E ₂=0.5*(D−2R _(d)−2G−E ₁) wherein E₁ is a diameter of the outer flangeportion of the electrode terminal, E₂ is a width of an exposed surfaceparallel to a surface of the electrode terminal in the outer surface ofthe second end of the battery housing, D is a diameter of the batteryhousing, R_(d) is a width of a round region at an edge of the batteryhousing measured on a plane, G is an exposure width of the outer gasketthrough an edge of the electrode terminal, W₁ is a maximum value amongdistances between any two points selected in an edge of the firstoverlapping region, and W₂ is a maximum value among distances betweentwo points where a plurality of linear lines passing through the centerof the electrode terminal meet an edge of the second overlapping region.48. The battery according to claim 27, wherein a ratio of a diameter ofthe battery to a height of the battery is greater than 0.4.
 49. Abattery pack, comprising a plurality of batteries according to claim 27.50. The battery pack according to claim 49, wherein the plurality ofbatteries are arranged in a predetermined number of columns, and whereinthe electrode terminal and the outer surface of the second end of thebattery housing of each battery of the plurality of batteries aredisposed to face upward.
 51. The battery pack according to claim 50,further comprising: a plurality of bus bars connecting the plurality ofbatteries in series and in parallel, wherein the plurality of bus barsare disposed above the plurality of batteries, wherein each bus bar ofthe plurality of bus bars includes: a body extending between electrodeterminals of adjacent batteries; a plurality of first bus bar terminalsrespectively extending in one side direction from the body andelectrically coupled to the electrode terminal of the battery located inthe one side direction; and a plurality of second bus bar terminalsrespectively extending in the other side direction from the body andelectrically coupled to the outer surface of the second end of thebattery housing of the battery located in the other side direction. 52.The battery pack according to claim 50, wherein an AC resistance of thebattery measured between the electrode terminal and the outer surface ofthe second end of the battery housing is 4 milliohms (mohm) or less. 53.A vehicle, comprising at least one battery pack according to claim 49.54. An electrode terminal for a battery, comprising: a body having a topsurface, a lower surface and an outer surface; an outer flange extendingfrom the outer surface of the body and capable of extending along anouter surface of a bottom of a battery housing; an inner flangeextending from the outer surface of the body, the inner flange beingabove the outer flange; and the top surface on the body capable ofcontacting a current collecting unit.
 55. The electrode terminal ofclaim 54, wherein the top surface on the body is above the inner flange.56. The electrode terminal of claim 54, wherein the top surface on thebody is flat.
 57. The electrode terminal of claim 54, further comprisinga recess between the body and the inner flange.
 58. The electrodeterminal of claim 57, wherein the recess has a first surface formed bythe outer surface of the body and a second surface formed by an uppersurface of the inner flange.
 59. The electrode terminal of claim 58,wherein the first surface and second surface are asymmetrical.
 60. Theelectrode terminal of claim 54, wherein an angle between the innerflange and the outer flange is between 0° to 60°.